I know my coworker will never see this but low key I wish he would one day
Why do you want him to see this message?
I don't know how to tell him how I feel. When I see him next I will ask him for his number. Then I will call him and avoid telling him that I stalked him on FB.
Sounds like you really admire him, but you need to just be up front with him. It is creepy and gross to stalk someone, and conceal those facts. The longer you hide these the harder it will be to truly confess your feelings.
You don't understand. I'm too shy to do it in person.
I can understand your shyness, but it is wrong to try and keep things from your coworkers. You should be open and honest with them so that they will be the same way with you.