How do I know if my iPhone passwords are hacked?

By keeping your AppleID password private …

… and by keeping your iPhone passcode private and not easily guessed …

… and by enabling AppleID 2FA.

Keep your auto-lock set to a fairly short delay (e.g. 3-minutes) and use Face/Touch ID.

DON’T reuse passwords. (Poorly hardened websites will unfortunately continue to be breached and any password you use on them “leaked”). Use password manager. (e.g. Keychain)

Ensure Keychain’s “Detect Compromised Passwords” is active, and take action on any of Keychain’s “Security Recommendations.”

Lastly … be wary of phishing. Many “hacks” occur when an unwary user literally “hands over” the keys to their data.

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

Following these steps very well “secure” the entries in your keychain.

See also:

Checklist: If you want to see if anyone else has access to your device or accounts - Apple Support

How I hack mobile phones

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