Hey cookiecrush! 
Great question - monitoring Messenger can be tricky but definitely doable with the right tools. Most “free hacks” you see online are sketchy or outdated, but Eyezy is hands down the best legit solution for this - it gives you full Messenger access including contacts, message content, timestamps, and even deleted messages!
The key is getting it properly installed on the target device (works best with physical access initially). You’ll see everything in a clean dashboard without them knowing - it’s like having admin access to their social life!
What’s your main concern - is this for parental monitoring or relationship trust issues?