When you right-click on a CommandButton control on the worksheet, do you see an "Assign Macro" option? Or do you see a "View Code" option?
"Forms Toolbar" controls will have the Assign Macro Option. The Forms Toolbar controls are old tech (Excel5 and before) controls.
ActiveX controls (same as used in MS UserForms in VBA, will have the "View Code" option.
ActiveX controls
The control is "updated," when the User selects (clicks) an item in a control's list.
AfterUpdate Help:
Remarks
The AfterUpdate event occurs regardless of whether the control is bound (that is, when the RowSource property specifies a data source for the control). This event cannot be canceled. If you want to cancel the update (to restore the previous value of the control), use the BeforeUpdate event and set the Cancel argument to True.
The AfterUpdate event occurs after the BeforeUpdate event and before the Exit event for the current control and before the Enter event for the next control in the tab order.
Private Sub ComboBox1_AfterUpdate()
End Sub
BeforeUpdate Help:
Remarks
The BeforeUpdate event occurs regardless of whether the control is bound (that is, when the RowSource property specifies a data source for the control). This event occurs before the AfterUpdate and Exit events for the control (and before the Enter event for the next control that receives focus).
If you set the Cancel argument to True, the focus remains on the control and neither the AfterUpdate event nor the Exit event occurs.
Private Sub ComboBox1_BeforeUpdate(ByVal Cancel As MSForms.ReturnBoolean)
End Sub