How can I know if I was hacked?

If you did not jailbreak your phone, your phone was not hacked.

Secure your accounts, including your Apple ID.

If you think your Apple ID has been compromised - Apple Support

Answer these questions:

1. Have you jailbroken your phone?
2. Has someone you don't trust had unsupervised access to your unlocked phone for more than a couple of minutes?
3. Are you a high-profile activist, journalist, or politician whose data would be worth hundreds of thousands of dollars to acquire?

If the answer to all of those questions is "No," your phone has not been hacked.