Lots of options!
Have him get down on the floor and play with him, read & sing to him, give him his baths & massages.
..The more interaction, the deeper the bonding
. Have your husband talk to your son, even telling him about what he did that day. The content of what's said isn't as important as the face to face time and 'conversation'--your husband can give him a bottle & read out loud from a book at the same time.