public CrosshairGroupHeaderElement HeaderElement { get; }

Public ReadOnly Property HeaderElement As CrosshairGroupHeaderElement

<Window x:Class="CrosshairCustomDraw.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:dxc="http://schemas.devexpress.com/winfx/2008/xaml/charts"
        Title="MainWindow" Height="414" Width="525">
    <Grid>
        <StackPanel>
            <dxc:ChartControl Name="chartControl1" Height="340" 
                              CustomDrawCrosshair="chartControl1_CustomDrawCrosshair">
                <dxc:ChartControl.CrosshairOptions>
                    <dxc:CrosshairOptions ShowArgumentLabels="True" 
                                          ShowArgumentLine="True" 
                                          ShowValueLabels="True" 
                                          ShowValueLine="True"/>
                </dxc:ChartControl.CrosshairOptions>
                <dxc:XYDiagram2D>
                    <dxc:XYDiagram2D.AxisX>
                        <dxc:AxisX2D>
                            <dxc:AxisX2D.CrosshairAxisLabelOptions>
                                <dxc:CrosshairAxisLabelOptions Pattern="{}{V:f1}"/>
                            </dxc:AxisX2D.CrosshairAxisLabelOptions>
                        </dxc:AxisX2D>
                    </dxc:XYDiagram2D.AxisX>
                    <dxc:LineSeries2D DisplayName="Series1">
                        <dxc:SeriesPoint Argument="1" Value="50"/>
                        <dxc:SeriesPoint Argument="2" Value="44"/>
                        <dxc:SeriesPoint Argument="3" Value="55"/>
                        <dxc:SeriesPoint Argument="4" Value="77"/>
                    </dxc:LineSeries2D>
                    <dxc:LineSeries2D DisplayName="Series2">
                        <dxc:SeriesPoint Argument="1" Value="22"/>
                        <dxc:SeriesPoint Argument="2" Value="11"/>
                        <dxc:SeriesPoint Argument="3" Value="9"/>
                        <dxc:SeriesPoint Argument="4" Value="8"/>
                    </dxc:LineSeries2D>
                </dxc:XYDiagram2D>
            </dxc:ChartControl>
            <Button Height="35" Content="Custom Draw Crosshair Cursor" Click="Button_Click"></Button>
        </StackPanel>
    </Grid>
</Window>

using DevExpress.Xpf.Charts;
using System.Windows;
using System.Windows.Media;

namespace CrosshairCustomDraw {
    public partial class MainWindow : Window {
        bool handleCustomDraw;
        public MainWindow() {
            InitializeComponent();
        }
        private void Button_Click(object sender, RoutedEventArgs e) {
            handleCustomDraw = true;
            chartControl1.CustomDrawCrosshair += chartControl1_CustomDrawCrosshair;
        }
        private void chartControl1_CustomDrawCrosshair(object sender, CustomDrawCrosshairEventArgs e) {

            if (!handleCustomDraw) return;

            // Specify the crosshair argument line color, dash style and thickness.
            e.CrosshairLineElement.Brush = Brushes.Aqua;
            e.CrosshairLineElement.LineStyle.DashStyle = DashStyles.DashDot;
            e.CrosshairLineElement.LineStyle.Thickness = 3;

            // Specify the back color for crosshair argument label. 
            foreach (CrosshairAxisLabelElement axisLabelElement in e.CrosshairAxisLabelElements)
                axisLabelElement.Background = Brushes.Blue;

            foreach (CrosshairElementGroup group in e.CrosshairElementGroups) {
                CrosshairElement element = group.CrosshairElements[0];

                // Specify the color, dash style and thickness for the crosshair value lines. 
                element.LineElement.Brush = Brushes.DarkViolet;
                element.LineElement.LineStyle.DashStyle = DashStyles.Dash;
                element.LineElement.LineStyle.Thickness = 2;

                // Specify the font size and background for the crosshair value labels.
                element.AxisLabelElement.FontSize = 14;
                element.AxisLabelElement.Background = Brushes.Red;

                // Specify the foreground and font size for the crosshair cursor label that shows series. 
                if (element.SeriesPoint.Value > 50) {
                    element.LabelElement.Foreground = Brushes.Green;
                    element.LabelElement.FontSize = 14;
                }
            }

            foreach (CrosshairElementGroup group in e.CrosshairElementGroups) {
                CrosshairGroupHeaderElement groupHeaderElement = group.HeaderElement;

                // Specify the text, text color and font for the crosshair group header element. 
                groupHeaderElement.Text = "Custom draw";
                groupHeaderElement.Foreground = Brushes.Red;
                groupHeaderElement.FontSize = 15;
            }
        }
    }
}

Imports DevExpress.Xpf.Charts
Imports System.Windows
Imports System.Windows.Media

Namespace CrosshairCustomDraw

    Public Partial Class MainWindow
        Inherits Window

        Private handleCustomDraw As Boolean

        Public Sub New()
            Me.InitializeComponent()
        End Sub

        Private Sub Button_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
            handleCustomDraw = True
            AddHandler Me.chartControl1.CustomDrawCrosshair, AddressOf Me.chartControl1_CustomDrawCrosshair
        End Sub

        Private Sub chartControl1_CustomDrawCrosshair(ByVal sender As Object, ByVal e As CustomDrawCrosshairEventArgs)
            If Not handleCustomDraw Then Return
            ' Specify the crosshair argument line color, dash style and thickness.
            e.CrosshairLineElement.Brush = Brushes.Aqua
            e.CrosshairLineElement.LineStyle.DashStyle = DashStyles.DashDot
            e.CrosshairLineElement.LineStyle.Thickness = 3
            ' Specify the back color for crosshair argument label. 
            For Each axisLabelElement As CrosshairAxisLabelElement In e.CrosshairAxisLabelElements
                axisLabelElement.Background = Brushes.Blue
            Next

            For Each group As CrosshairElementGroup In e.CrosshairElementGroups
                Dim element As CrosshairElement = group.CrosshairElements(0)
                ' Specify the color, dash style and thickness for the crosshair value lines. 
                element.LineElement.Brush = Brushes.DarkViolet
                element.LineElement.LineStyle.DashStyle = DashStyles.Dash
                element.LineElement.LineStyle.Thickness = 2
                ' Specify the font size and background for the crosshair value labels.
                element.AxisLabelElement.FontSize = 14
                element.AxisLabelElement.Background = Brushes.Red
                ' Specify the foreground and font size for the crosshair cursor label that shows series. 
                If element.SeriesPoint.Value > 50 Then
                    element.LabelElement.Foreground = Brushes.Green
                    element.LabelElement.FontSize = 14
                End If
            Next

            For Each group As CrosshairElementGroup In e.CrosshairElementGroups
                Dim groupHeaderElement As CrosshairGroupHeaderElement = group.HeaderElement
                ' Specify the text, text color and font for the crosshair group header element. 
                groupHeaderElement.Text = "Custom draw"
                groupHeaderElement.Foreground = Brushes.Red
                groupHeaderElement.FontSize = 15
            Next
        End Sub
    End Class
End Namespace

foreach (CrosshairElementGroup group in e.CrosshairElementGroups) {
    CrosshairGroupHeaderElement groupHeaderElement = group.HeaderElement;

For Each group As CrosshairElementGroup In e.CrosshairElementGroups
    Dim groupHeaderElement As CrosshairGroupHeaderElement = group.HeaderElement
    ' Specify the text, text color and font for the crosshair group header element.