I don't think you can make your mouse pointer lock onto a field without a 3rd party software. But you can make the focus to a field when you open a form. So you can just push enter then if it's a button.

Control.SetFocus
https://599cd.com/site/courselist/access2013/developer/d13/

Thanks for that Adam

You can move the mouse pointer with VBA, but it requires WINAPI calls, which I prefer not to do. Like Adam said, SetFocus is good, and you can change the color of the field that has focus with some Conditional Formatting.