Since the start of Season 6 in Fortnite players have been noticing weird noises coming from different parts of the map. A lot of people have not been able to understand where the noises have been coming from. A Fortnite player “HypeX” revealed via twitter that the noises are actually coming from the Tower at the center of the map.
Hypex made a complication of all the different sounds into one video, that reveals some dinosaur noises and what appears to be Foundation screaming, possibly in pain.
Still having known the source of the strange noises it is unclear why the noises are actually coming. This could be related to a future update or DLC that might come later into the game. (Source)