Umm... Well he probably won't do it until he gets used to you, but Teeney likes to follow my finger if I run it along the glass :)
Some people teach their bettas to go through little hoops but you need food to train lol. Just be sure not to touch him, it's not good to touch your betta because it removes the slime coat which protects them against illness.
Or you can put your finger in the tank and see if he bites you. Lol. Teeney bites. It doesn't hurt, but it does scare me lol. Their teeth are small xD