My iPhone 6s was compromised by hackers trough malware and even web inspector/experimental features as of June 2020. I discovered after all my accounts were locking me out and I would no longer receive text messages from my bank or other account versifications such as (yahoo/Gmail/wells Fargo/Apple ID/ICloud/my verizon.com/facebook/Instagram/Google)
iPhone 6s, iOS 12
See these security-related documents, especially the first two for now.
If you think your Apple ID has been compromised https://support.apple.com/en-us/HT204145. From the link, among other things, Change your Apple ID password and choose a strong password.
Security and your Apple ID https://support.apple.com/en-us/HT201303
iCloud security overview https://support.apple.com/en-us/HT202303
Ways to keep your information safe on Mac https://support.apple.com/en-gb/guide/mac-help/mh11402/mac
Using app-specific passwords https://support.apple.com/en-us/HT204397
Use Two-factor authentication for Apple ID https://support.apple.com/en-us/HT204915
__________
And, if you can Check your Apple ID device list (https://support.apple.com/en-us/HT205064) and remove any device that shouldn't be signed in using the steps in the link.
If there are none that shouldn’t be signed in, then you should not have a problem at this point. But, if an unauthorized device is signed in, Change your Apple ID password https://support.apple.com/en-us/HT201355
Here is What to do after you change your Apple ID or password https://support.apple.com/en-us/HT204071
For Apple Support help with your problem, use:
Get a call from Apple support to help solve your problem https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362
Apple ID Support https://support.apple.com/apple-id
Apple Support Twitter https://twitter.com/AppleSupport
Apple ID account security for country-specific and region-specific
My Apple ID and Icloud have been compromised by hackers
