look in on (someone or something)
To check on a person or thing by visiting or looking from a short distance. Since I'm going to be working late tonight, can you look in on my cat and see if she has enough food in her bowl? The boss likes to look in on the interns every so often to make sure they always have something to do.
look in on
Pay a brief visit, as in I'm just going to look in on Gail and the new baby; I won't stay long. [c. 1600] Also see look someone in the face.
look in on
To visit: I look in on my grandparents each weekend.