Hide phone number option from others visitors by user when add listing

giving the users ability to hide his phone number by checking box under the phone number field in the submitting page , because somtimes the user want to receive by msg in the site does not want every visitors to call him just for 1 quations so the user want the ability so his phone number hidding by other users and contact only by messege in the site
how to create check box under the phone number field with name “”hide my number from others “”

and after checking the box the other visitors must see in the list page “”sorry the user has chosen to hide his phone number from public please contact him by message system in site “”