How to clean my iPhone from a virus’s and hacked

You probably saw a pop-up message (falsely) claiming your device was infected with 8 or 16 or 65536 viruses, or (falsely) suggesting thar your device was hacked, or showing you a password of yours acquired from a breach and (falsely) claiming they can access your camera.

It’s that latter case that’s trouble though, if you’ve been re-using your passwords.

Some info on common scams: Scam Pop-ups, Scam Viruses, Scam Receipts… - Apple Community

The factory reset seems premature right now, without more information on what’s happening here. “YOU ARE INFECTED WITH 4 VIRUSES!” pop-ups are ubiquitous, unfortunately. And harmless. Unless you follow through and hand over your credentials, or install some sketchy app.

I agree with the above. If you want to reset the phone, do a factory reset. Do not restore a backup made during the time you think the phone was hacked.

Restore to Factory setting.      

Restore - If you see an error when you update or restore your iPhone, iPad, or iPod

iPhone > Settings > Passwords > Security Recommendations

Password re-use is Bad News. Those passwords get exposed when some service gets breached, then the nefarious will try the same email and password everywhere else. If you’re re-using passwords as most of us have, your access will almost certainly get breached.

As for Facebook, no idea how (if?) account recovery works over there.

Odds are they got into your facebook account through a data breach (though hacking or spyware is a possibility). Your iphone is probably not the issue here.

What makes you think your iPhone is hacked or infected? iPhones are extremely secure against these things.