Combobox Display member and Value Member

Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        Dim key As String = DirectCast(ComboBox1.SelectedItem, KeyValuePair(Of String, String)).Key
        Dim value As String = DirectCast(ComboBox1.SelectedItem, KeyValuePair(Of String, String)).Value
        MessageBox.Show(key & "   " & value)
    End Sub

'' Add items to combobox
    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim comboSource As New Dictionary(Of String, String)()
        comboSource.Add("25 Year", "Nishant")
        comboSource.Add("26 Year", "Ravi")
        comboSource.Add("27 Year", "Mohan")

        ComboBox1.DataSource = New BindingSource(comboSource, Nothing)
        ComboBox1.DisplayMember = "Value"
        ComboBox1.ValueMember = "Key"
    End Sub