The mysterious spider in my room

 A few days  ago I left the window in my room open which caused a lot of bugs to come in. The first thing that my sister spotted was a dead cockroach right on the ground she caused a ruckus so my mum came and picked it up with a tissue. After that my sister discovered a tiny slug on her pillow and then we moved out of the room.  The day after the incident I was working in the bug room when I realised that there was a tiny black spider on the ceiling. I thought nothing of it because it I thought it was dead because the spider wasn't moving. Today I looked up on the ceiling to find the spider had moved in the night, and it was moving closer and closer to the window. But my desk is right next to the window so it's basically right above my head  but if it dangles down on it's web it won't be above my head and instead on my head.