I suspected my mobile number has been hacked as I got messages from facebook about someone registered and verified my mobile number with another unknown fb account and fb password reset code while I didn't register or reset anything. Does anyone know what should I do? Thanks!
Your number hasn't been hacked, its most likely a Phishing text trying to get you to log in to your Facebook account so they can take over your account.
You can forward that text message to Fido by sending it to 7726 (SPAM) they can audit it and try to block these types of spam text.