To see iMessage history with a phone number, you'll need to access the Messages app on your iPhone or iPad. It's pretty straightforward, but you'll need to make sure you're signed in with your Apple ID to get started. From there, you can begin to uncover the secrets of your iMessage history.
Now, here's where things get interesting. When you search for a specific phone number in the Messages app, you'll be able to see all the conversations you've had with that person. It's like taking a trip down memory lane, but instead of old photos, you're looking at iMessage conversations.