Is it the only chick you have? How old and can you attach a photo? Is the heat lamp the only heat source you have? What is the temperature inside the brooder with the lamp on vs turned off? Does it have food and water available 24/7?
Chicks will chirp loudly when they need something, food, water, warmth, companionship. It is a distress call meant to call for their mother and/or siblings. See if it is hungry, thirsty, cold or just lonely. Sometimes there will be a chick that is just chirping to get your attention. I had one in my last batch who chirped for no reason at all. This phase only lasted a week or so.
You should not turn the heat lamp off unless the chick is already well feathered and the room temp is safe for it. You should also make sure they can get away from the heat inside the brooder if it ever gets too hot. People usually have the heat lamp on one side of the brooder with a cooler area on the other side so they can go where they are comfortable.