Private Sub Worksheet_Activate()
Dim obj As Object, i As Boolean
    For Each obj In Tabelle1.OLEObjects
        If obj.Name <> "Button_CB1" Then
            i = False
        Else
            i = True
            Exit For
        End If
    Next
    If i = False Then
        CB_Create
    Else
        Buttons_Aktivieren
    End If
End Sub


Sub CB_Create()
    With Tabelle1.OLEObjects.Add(ClassType:="Forms.CommandButton.1", _
                          Left:=Tabelle1.Cells(1, 1).Left + 6, _
                          Top:=Tabelle1.Cells(1, 1).Top + 2, _
                          Width:=30.75, _
                          Height:=18)
      .Name = "Button_CB1"
      .Object.Caption = "Test"
    End With
Application.OnTime Now + TimeValue("00:00:01"), "Buttons_Aktivieren"
End Sub