Gday, Welcome to Linux.org
Are you using a Linux distro ?
Perhaps your question may be better asked of the people at Facebook ?
How sure are you that your account there was hacked?
Hacking another persons account is an offence....has this been reported to Police/authorities ?
Check this facebook help article. At the bottom you have the answer to "Learn what to do if you think your account was hacked", and otherwise you should be able to contact facebook support somehow. I don't even have facebook and I was able to find this information.
Gday, Welcome to Linux.org
Are you using a Linux distro ?
Perhaps your question may be better asked of the people at Facebook ?
How sure are you that your account there was hacked?
Hacking another persons account is an offence....has this been reported to Police/authorities ?
Not necessarily a Linux problem, could be that someone guessed your password like what happened to Trump's twitter account. Then it could be that someone cracked your account using a dictionary password cracker, this is a way of automatically guessing your password from a dictionary of passwords and not needing access to your system in order to get the password.