How to protect iPhone from getting hacked?

There are several things you can do - and not do - to protect your iPhone from being hacked. The include:

• Do not share the password with anyone else.
• Do not allow anyone to sign out of your ID and sign in to theirs.
• Use a strong passcode.
• Turn on Find My iPhone.
• And more ideas described on this Apple Support page: Use the built-in privacy and security protections of iPhone

Run Safety Check on your phone.

How Safety Check on iPhone works to keep you safe - Apple Support

Do not jailbreak it or let anyone else do it. A non-jailbroken phone cannot be hacked.