To hide your mobile number from everyone on Facebook or to have it available to friends or to a customized list of friends only, you can by setting the relevant permission.
For information on creating a list visit creating lists in facebook
Go to your timeline by clicking your name at the top right or top left of the page
Select Update info
Scroll down to Contact info
Select Edit
Select the dropdown menu icon and it will give you the options of who you wish to have access to your mobile number, for total privacy so it isn’t visible to anyone who views your profile select Only me
Scroll down
Select Save
