iPhones are extremely secure. The fact that your bank account may have been hacked does not mean your phone has been hacked. Unless your phone has been jailbroken, the likelihood that it has been hacked is infinitesimally small. Could your Apple ID have been compromised? Yes. But, again, that doesn't mean your phone has been hacked.
If you believe your Apple ID has been compromised, start here:
If you think your Apple ID has been compromised - Apple Support