Your account may have been hacked if:
You find other devices listed under "Where You're Logged In" in the Settings>Security and Login that don't belong to you or you don't recognize.
[caption id="attachment_107528" align="aligncenter" width="602" class="none"] Source: fastcompany.com[/caption]
You see changes to your personal information on your account profile (such as current location or birthday)
You spot activity on your account that you didn't initiate. One sign of a breach is the appearance of shares and posts on your timeline, showing activities you weren't engaged in. Your friends may also report getting strange messages from you or unusual activity on their timelines.
Another sign of a possible hacking attempt is receiving an email that says someone logged into your account or changed your password and it wasn't you.
You notice friend requests sent to people you have no connection with.
You discover messages on your Messenger that were sent to people you don't know.