Pop up said your iPhone has been hacked

That's probably a scam attempt to get personal info from you. Ignore that message and DO NOT respond.

To feel more comfortable, change you Apple ID password, as per this support article:--> If you think your Apple ID has been compromised - Apple Support

Regards

Giulio

Yes, scam attempts can come via SMS, e-mail messages, Popups, Phone calls, etc.

See this guide:--> Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

Regards

Giulio

Delete the message and move on.

An iPhone can't be hacked unless you jailbreak it.