If you've added your phone number to Facebook for 2FA security, it can be used to search for you - BetaNews

1. If you've added your phone number to Facebook for 2FA security, it can be used to search for you  BetaNews
2. PSA: Don't give out your phone number for Facebook 2FA, use an app instead  The Next Web
3. Facebook Lets Anyone View Your Profile Using Your Phone Number  Fossbytes
4. Facebook won't keep your two-factor phone number truly private  Engadget
5. Facebook doesn't allow phone number 'look up' opt-out  Fox News
6. View full coverage on Google News