How to add an event if change occured in combo box or text box

I am trying to add an event like a button show or hide or add a label if any of these current fields change in the userform

These are either combo box or text box

Some of these values are already there from the part properties

I looked thru the VB help files and couldn't find a working solution for this.

Can someone please help me with a proper code.

Thanks!

SolidworksApi macros