How do I know if my phones been jail broken

If it is truly new (as purchased from Apple or an Apple Approved Reseller) it hasn’t been jailbroken. If it is a used phone the previous owner should have done this→What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support. If they did when you turn it on it should say “Hello”, then lead you through setup. If this isn’t what you see return the phone for a refund.

A non-jailbroken phone cannot be hacked. Unless you jailbroke your phone or gave it to someone you did not trust, then your phone is not jailbroken.