Is my iPhone hacked?

NO, your phone hasn't been hacked. That is 100% a scam. No one can hack your phone and no company can possibly see inside your phone. Delete the scam message. Don't give them any information and most definitely don't buy their useless software to fix an issue you don't have. Also whatever website you were on when the message was delivered should be avoided. They are paid by the scammers to try to trick you into buying these worthless tools.

Read this --> Recognize and avoid social engineering schemes including phishing messages, phony support calls, and other scams - Apple Support

It's a scam. Delete and ignore.

You haven’t been hacked yet, but if you press any buttons on that screen then you’ll probably be redirected to a screen to where you enter Apple account details, and then you actually will get hacked. That dialogue is a complete fake. Someone is most likely trying to steal your Apple account information. In one word: SCAM.

Your phone is not hacked. The message that you saw was NOT from Apple.

You know this by simply looking at the web address at the bottom of your screenshot........

[Edited by Moderator]

Absolutely a scam. Similar messages may tell you to call a number for "help". The numbers in such messages belong to criminals, and the only "help" you will get is help in ripping you off!

U.S. Federal Trade Commission – How To Spot, Avoid, and Report Tech Support Scams

"Tech support scammers may try to trick you with a pop-up window that appears on your computer screen. It might look like an error message from your operating system or antivirus software, and it might use logos from trusted companies or websites. The message in the window warns you about a security issue on your computer and tells you to call a phone number to get help.

…

If you get this kind of pop-up window on your computer, don’t call the number. Real security warnings and messages will never ask you to call a phone number."

It’s usually an ad for an add-on VPN app that doesn’t solve the problem that this ad falsely claims to have found, doesn’t provide any appreciable additional security, and badly solves a problem that hasn’t existed in a decade or so, but badly solves it in a way perfect for collecting personally-identified metadata.

Most things you’ll read using words including HACKER and VIRUS is probably also an advertisement, or is entertainment, until proven otherwise.

Apple also has vastly better grammar.