Your Apple iPhone has been hacked. All operations on your device are being tracked by the hacker. Immediate action is required!

What I do how can I stop it

Scam!

Do not click on the message, follow any link in it, or call any phone number in it. This is a "phishing" message sent by criminals. The message is a pure lie, and its intent is to frighten you into contacting the criminals for "help". They will then "help" you out of things like the contents of your bank accounts.

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

A location request and suggestive message was sent from my message app to a good friend of mine. I contacted Apple Support and other than resetting network settings and rebooting, I was given no explanation as to how those messages had been sent when I was not the one who sent them.

Also see: Your Apple iPhone has been hacked. All op… - Apple Community