https://wordmvp.com/FAQs/Userforms/AddRightClickMenu.htm
Private Sub TextBox1_MouseDown(ByVal Button As Integer, ByVal Shift As Integer, ByVal X As Single, ByVal Y As Single) If Button = 2 Then Call ShowPopup(Me, Me.Caption, X, Y) End If End Sub
Note: This feature works best if you set the following properties for the TextBox:
EnterKeyBehaviour = True
MultiLine = True
ScrollBars = fmScrollBarsBoth or fmScrollBarsVertical