To find out if your critical personal information was hacked, simply go to the Equifax web site and enter all of your critical personal information in the form provided.
No joke, no sarcasm. This is the only way to find out.
I suppose there's other ways. If you find your bank account is wiped, its possible you may have been hacked. Or if you begin receiving credit card bills for millions of dollars of purchases you can't quite recall making, its possible you may have been hacked.