Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As _
   System.EventArgs) Handles Button1.Click
        Dim Textbox As New TextBox
        With Textbox
            ' Hier Einstellungen Top Left Multiline etc.
        End With
        Me.Controls.Add(Textbox)
        AddHandler Textbox.Click, AddressOf TextBox_click
 
    End Sub
 
    Private Sub TextBox_click(ByVal sender As Object, ByVal e As _
      System.EventArgs)
        Dim Textbox As TextBox = sender ' Und da hast du deine Textbox wieder
        MsgBox(Textbox.Text)
    End Sub