[DXCategory("Events")]
public event EventHandler DataSourceChanged

<DXCategory("Events")>
Public Event DataSourceChanged As EventHandler

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

public partial class Form1 : DevExpress.XtraEditors.XtraForm {
    public Form1() {
        InitializeComponent();
        // Binds the lookup to data.
        lookUpEdit1.Properties.DataSource = Employee.GetSampleData();
        // Sets the lookup's data fields.
        lookUpEdit1.Properties.DisplayMember = "FullName";
        lookUpEdit1.Properties.ValueMember = "ID";
        // Sets the lookup's value. Selects the first record.
        lookUpEdit1.EditValue = 0;
    }
}

public class Employee {
    public Employee(int iD, string firstName, string lastName) {
        ID = iD;
        FirstName = firstName;
        LastName = lastName;
    }
    public static List<Employee> GetSampleData() {
        return new List<Employee>() {
            new Employee(0, "Bart", "Arnaz"),
            new Employee(1, "Leah", "Simpson"),
            new Employee(2, "Arnold", "Schwartz"),
            new Employee(3, "William", "Zimmer"),
            new Employee(4, "Samantha", "Piper")
        };
    }
    // The 'ID' field must contain unique values.
    public int ID { get; private set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    [Display(Order = -1)]
    public string FullName {
        get {
            return string.Format("{0} {1}", FirstName, LastName);
        }
    }
}

Imports System
Imports System.Collections.Generic
Imports System.ComponentModel.DataAnnotations

Partial Public Class Form1
    Inherits DevExpress.XtraEditors.XtraForm

    Public Sub New()
        InitializeComponent()
        ' Binds the lookup to data.
        lookUpEdit1.Properties.DataSource = Employee.GetSampleData()
        ' Sets the lookup's data fields.
        lookUpEdit1.Properties.DisplayMember = "FullName"
        lookUpEdit1.Properties.ValueMember = "ID"
        ' Sets the lookup's value.
        lookUpEdit1.EditValue = 0
    End Sub
End Class

Public Class Employee
    Public Sub New(ByVal iD As Integer, ByVal firstName As String, ByVal lastName As String)
        Me.ID = iD
        Me.FirstName = firstName
        Me.LastName = lastName
    End Sub
    Public Shared Function GetSampleData() As List(Of Employee)
        Return New List(Of Employee)() From {
            New Employee(0, "Bart", "Arnaz"),
            New Employee(1, "Leah", "Simpson"),
            New Employee(2, "Arnold", "Schwartz"),
            New Employee(3, "William", "Zimmer"),
            New Employee(4, "Samantha", "Piper")
        }
    End Function
    ' The 'ID' field must contain unique values.
    Private privateID As Integer
    Public Property ID() As Integer
        Get
            Return privateID
        End Get
        Private Set(ByVal value As Integer)
            privateID = value
        End Set
    End Property
    Public Property FirstName() As String
    Public Property LastName() As String
    <Display(Order := -1)>
    Public ReadOnly Property FullName() As String
        Get
            Return String.Format("{0} {1}", FirstName, LastName)
        End Get
    End Property
End Class