Facebook does not let you know who is looking at your profile, but you can check your privacy settings to determine whether someone has the opportunity to spy on your profile. Certain privacy settings, such as setting your profile so everyone can view it, or friends of friends, can make it so that people you don't know are able to view your profile. You can change your privacy settings so that only your direct friends list is able to view your profile, instead of anyone who is friends with your friends.
Bring up your Facebook profile.
Click "Account" and then "Privacy Settings."
Choose from the three main categories or customise your settings. "Friends Only" is restricted to people on your Friend list. "Friends of Friends" expands the list of people who can view your profile to all those friends of your friends. "Everyone" is just as it sounds -- your profile is available for public viewing.
Choose "Customize settings" to fine-tune access. You can adjust the viewing settings for each type of content that you can post on Facebook.