When creating a Facebook account, the system automatically assigns the user an identification number, known as the Facebook ID. Facebook allows the user replace their ID with username. If you are using a custom username for your Facebook profile or page, then unique profile ID will not appear.
Many tutorials give you an instruction by clicking right mouse on image profile to find your unique ID. Now I will tell you even easier to find your Facebook profile ID.
How To Find Facebook Profile/Page ID?Just type at your address bar: https://graph.facebook.com/YOUR USERNAME or PAGE
Or type your username below and hit Get Facebook ID