To peek at something is to look at it; however, a person peeks in secret, discreetly, or privately.
In these sentences, the word "peek" is a verb:
Linda peeked out the window all day as her new neighbors moved into the house next door.
The boy was caught peeking at a Playboy magazine.
Don’t peek at the test until it’s time to begin.
The children peeked at their Christmas presents weeks before they received them.
Sometimes this word is used as a noun:
Do you mind if I take a peek at the report? (I want to look at it very quickly.)
Everyone was trying to get a peek of Jennifer Lopez as she left the hotel.
Take a peek over the fence and see what they’re doing next door.
Let’s try to get a peek.
He’s peeking at you.
Note: A popular game to play with babies is called "Peek-a-boo." You cover your eyes with your hands and then quickly remove your hands to show your eyes. This is done again and again to the amusement of a baby.