How to use sub in created checkbox

I am doing some stuff in excel VBA and I got a problem. When I clic on a button, ActiveX checkbox is created (I need this checkbox for some other task) and I would like to have that when the checkbox is "true" the background color is green (when false it's red). I know how to code this manualy into checkbox created by me. But I dont know how to assign this code to checkbox created by vba. thank you for answers :)