Populate phone number from contact to all related cases of that contact

Hi Experts,

I have one phone number field on a contact in CRM and I need to update that phone number for all the related cases in "Contact Person Phone number" field which is another field on a case. whenever the phone number is updating on contact it should be updated for all related cases within their contacts person phone number field.

Can you help with some OOB way to do this or I need to write a script for the same?

Thanks.