peep at (someone or something)
To get a quick, cursory, often sneaky or surreptitious look at someone or something. I peeped at the boss's computer, and it looks like there's a round of layoffs on the way. Campus guards caught him trying to peep at the women getting changed in their locker rooms.
peep at someone or something
to get a glimpse of someone or something, as if looking through a hole. I peeped at Tom through the Venetian blinds. Look in the microscope and peep at this bacterium.