Wrong letters when I'm typing with Macbook Pro
This unicode combination can be produced when holding down the alt/option key on your Mac's keyboard. If you google this issue, there is a thread from 2013/14 describing a solution to this issue.

Here are the summarised steps to revert they keyboard back to its intended use:


Open system preferences
Select accessibility
Select keyboard
Enable sticky keys
Press option twice quickly to enable sticky and once more to turn it off (option key must be enabled if you previously disabled it in modifier key controls)
Problem solved! - Turn sticky keys off again


I can verify that these steps are still valid for macOS High Sierra but do let me know how you get on.