Siri activates when i press the Home button, but doesn't activate when i say "Hey Siri,"

You may not have Hey Siri turned on in Settings. If you do, you may want to shut it off and then turn it back on so Siri will go through the process to recognize your voice again. Both options are covered in this support article:

If "Hey Siri" isn't working on your iPhone - Apple Support

Advise if you have reviewed the attached support article and verified the Hey Siri option in settings. Also have you verified Microphone functionality in an App such as Voice Memos, FaceTime, or Audio Messages?

Read and follow the article linked above.

Siri activate when press home button but doesn’t work when say hey Siri

Siri doesn’t activate when saying hey Siri