IT (and some professors) can likely check the user agent of the device accessing it (which tells you the operating system and browser used), so they could know whether it was a phone that accessed it or a laptop. I have used it myself, and caught a student accessing his Canvas exam on his phone (while he left the exam room).
Alternatively, both IT and professors can check what you did on the activity history, whether your laptop accessed only the main course page, or if it accessed a specific file.
These can be used as proof against you but, if you really did nothing, it can also help exonerate you. I don't know what the IT policy in your school is, whether they are willing to share that information with you before you write the report (to tell the truth, I don't know what my University's policy on that is, either), but you might consider checking?