How to check if my iPhone is hacked?

There are no absolutes here. Nor can there be.

All that likely happened here was that you have identified yourself as someone willing to click on spam links, which means you’ll be targeted with more, and likely that your email address will be worth to sell to other scammers and spammers.

If you’re a political dissident, investigative reporter, or have direct or indirect access to sensitive or confidential or financial data, or similar value to a well-funded adversary, the above calculation here might shift.

Add-on anti-malware cannot scan the storage of an iPhone. That access is blocked by App Store rules.

Old batteries and failing batteries can get warm, as can devices with confused or befuddled or buggy apps having gotten busy.

You're fine. You haven't been hacked. And, as long as you didn't provide personal details to anyone, you have nothing to be worried about.