Follow these steps below :
1. Login to your facebook account,then go to profile.Copy the address on address bar.It will show your facebook ID or username. egs : "https://www.facebook.com/ajengpunyadia" or "https://www.facebook.com/profile.php?id=100003745921644"
2.Log out from your facebook,then paste the address on address bar.look at the pictures below :
When the page shows like picture1,it means your facebook account is a "bit" vulnerable,and when the page shows picture 2,it means your account is more secure,maybe you made private setting on your account.
Let's go to the next step if the page shows picture 1.Mostly,hacker will hack your email before hack your facebook account.With these steps below we will try to guess the facebook email.
Open www.facebook.com and then " forgot your password " under password box. and the page will be like this :
Put your facebook username or ID on "Enter your facebook username box",then click search.See picture.
It will look like this
Read this !!! how to secure your facebook account.
Take 30 days challenge !!!