How do you make a button trigger an OnBeginDrag?

Hey -- Newcomer to game dev here -- I'm trying to make a button that, upon clicking and holding click, will immediately add something to their mouse that they can drag around. My only problem is that I need a way to call OnBeginDrag from a function that the button's On Click() will recognize, which needs an input of a PointerEventData. Anyone know how to do this? Am I doing this completely wrong?

Thanks for your help!