Vim - Is Capslock on?

When I work with Vim I almost never look at my keyboard (like it should be!) and this is great, but sometimes, unknowingly I hit the CapsLock key and causes me to yell at my screen.

Because, you know, j is not the same as J in normal mode (and so on).

So instead or mapping CapsLock to say Ctrl I want to display an error message that will warn me in normal mode if this is the case.

Is there a way for Vim to tell if you have CapsLock enabled?

Note: I prefer a VimScript/VimL solution for portability and because I want Vim to notify me and not depend on the actual system.