https://www.theverge.com/2018/10/12/17968562/facebook-hack-how-to-tell-if-data-stolen

Facebook detailed today exactly what type of information was accessed during a wide-scale hack last month. It included users’ names and contact info, and in many cases, personal details like religion, locations, and more.

This data was viewed on 29 million people, and now Facebook is offering a way to see whether your account was broken into and what information was seen. If you visit Facebook’s Help Center, a notice at the bottom will explain whether your account was affected. If it was, it’ll state what information was taken.