You should suppress your mobile number, especially if you are being stalked. This is because your number can be used in many different ways to attack you. For example, it can be used to find out whether you have accounts with certain messengers. It can also be used for registrations or annoying calls or messages.
Also be aware that suppressing the phone number only means that it is not displayed on the other party's phone. Your number will still be saved in the call logs (traffic data) of the providers involved. The authorities can therefore trace your call despite the suppressed number. Use anonymous SIM cards if you need real anonymity.