Ticket custom fields and user fields

Hey there,

I'm currently looking to store the clients phone number while creating a new request. I didn't find any option regarding this matter in the Forms/Fields, only for email field that is added automatically in the form when the user is not signed in. Is there a way to save this phone number custom field inside the user profile contact details information automatically ? Currently our agents have to copy the number from the custom field in the ticket to the user profile. 

Thanks !