How to Know if a Guy Likes You

See if he makes eye contact with you when you're around: If you notice the guy staring into your eyes, try matching his stare with a grin that you can keep for a few seconds. He could be interested in you if he doesn't look away, especially if he grins back. Remember that this might simply be him acknowledging you, or he could be in the habit of gazing at everyone in the eyes. On the other side, some males are really timid when they like someone, so if he's truly into you, he could make less eye contact.

Pay attention to whether he smiles around you: You can't help but grin when you see someone you like. If the person you're with always lights up when he sees you, it might suggest he has a crush on you. He could also just grin at you because you're pals, so don't leap to conclusions.

Consider whether he appears anxious or uneasy in your presence: When a guy likes someone, he may become a bit shy. If a guy flushes, stammers, or becomes quiet when you approach him, he may have a crush on you, however, he might just be genuinely bashful.
If you see a guy doing this and you like him, give him a small grin or a pat on the arm to comfort him. It could put him at ease.

Reference
https://www.wikihow.com/Know-if-a-Guy-Likes-You