What can I do if neighbor spits on my car?

A man in my building spits on my car every day. He doesn’t do it in front of me but does it when I am not around. Sometimes, I find chewing gum on my car cover or some kind of liquid poured on it. Occasionally, there is gutkha beside my car in the parking. There is only one window above my car that belongs to this man. I tried speaking with him, but he denies doing this. I have photographs as evidence. Kindly suggest what I should do.