How do I know if my iPhone 13 has been hacked

See -> If you think your Apple ID has been compromised

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

To keep your Apple ID account secure, see the following Apple articles:

Manage and use your Apple ID

Manage and use your Apple ID – Apple Support (UK)

See who has access to your device or accounts

See who has access to your device or accounts – Apple Support (UK)

Recognize and avoid phishing messages, phony support calls, and other scams

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

Phony "tech support" / "ransomware" popups and web pages

Phony "tech support" / "ransomware" popup… - Apple Community

Identify and filter junk mail in iCloud

Identify and filter junk mail in iCloud - Apple Support

Identify legitimate emails from the App Store or iTunes Store ->

Identify legitimate emails from the App Store or iTunes Store – Apple Support (UK)

Set up iCloud Keychain

Set up iCloud Keychain - Apple Support

Create a strong password for your Apple ID, It is best if your password consists of eight or more characters and include upper and lowercase letters, and at least one number. You can also add extra characters and punctuation marks to make your password even stronger. 

Never provide your password, passcode, security questions, verification codes, recovery key or any other account security details to anyone else. Apple will never ask you for this information.

See also the following Apple articles:

About the 'Trust This Computer' alert on your iPhone, iPad, or iPod touch

About the 'Trust This Computer' alert on your iPhone, iPad, or iPod touch - Apple Support

Authorize or deauthorize your computer for iTunes Store purchases

Authorize or deauthorize your computer for iTunes Store purchases - Apple Support 

Get a verification code and sign in with two-factor authentication

Get a verification code and sign in with two-factor authentication - Apple Support

Check your Apple ID device list to see where you're signed in

Check your Apple ID device list to see where you're signed in - Apple Support

• if you see devices that don't belong to you, delete from your account.

You can call Apple support ask the customer service rep to view/ share your screen. Show them why you think you’ve been hack. If they see any indication they can reach out to a team lead. The team lead will advise them how to direct you. If an extreme circumstances are displayed. A team lead can send a linked scanning test to your device, under the Privacy settings, Share iPhone Analytics.

First an most importantly change your Apple password & check all your setting including privacy on your device. There is also several features under the Screen Time setting to block unwanted changes & usage.