Suspicion of hacking

if your iOS device is not jailbroken then the tools a hacker would require are not available to software developers.

If you think your Apple ID is hacked you should reset the password.

https://support.apple.com/en-us/HT201355

Is there something specific that makes you think you're hacked?

Why do you think it is hacked? More information would help.

You can also add 2 Factor Authentication to your account for more security. If the attempts continue, you might want to consider a name change.

Apple ID has been compromised

Note the restrictions in the article.

Apple ID Name Change

 What to do after you change your Apple ID or password - Apple Support     I suggest doing this before you change your Apple ID or password.

 Apple ID -Two-factor authentication

 Two Factor Authentification availability

 Apple ID - Using app-specific passwords

Apple ID - Two Step Verification App Specific Passwords

Apple ID - Two Step Verifications FAQ

Knowing your conversations and txt messages, does not mean that your iPhone is hacked.

It is far more likely that what ever service you are using to send them has been hacked.

If it is not jail broken, it is not being hacked.

What is it doing which makes you think that it is?

Did you try changing your password or any of the other suggestions made earlier?

If the service you are using has been hacked, changing your password won't help.