I have a handful of experiences with the unseen or the un-explainable. About 20 years my family was living in student housing at a school of theology in Illinois, the housing itself was around a hundred years with a lot of strangeness to it from real to unreal.
During our stay there we had neighbors next door with a lab who loved tennis balls and seemed to play with them almost all the time. The neighbors with the lab moved out after about two years due to one of them having to go and do their church stint. Not long after they moved out I often would hear a tennis ball being bounced the apartment next door. I thought nothing of it like it was a trick of my mind until I got blamed for bouncing a ball in the middle of the night. Our downstairs neighbor called and complained that someone was bouncing a ball right where my bedroom was. My father questioned me and I told him that I was no playing around at night and I had no clue what he was talking about.
It was not until about five or six years after said call I really thought about it and I remembered that I indeed was not playing at night but I too remember hearing a ball bouncing at night. To this day I am not sure if the dog had past once they had moved or his spirit was there at the student housing apartment. Could it have been some strange residual energy of the dog stayed, or it was a spirit who just happened to be there who played with the dog.