About 3 years ago, I worked in a job that I didn't particularly like. Also, the building was supposedly haunted - it was a child care centre.

I experienced a strange thing one morning at this job.
I started work at 6.30am but I always got there at 6am so I could open everything up before any kids arrived. I made sure both front doors were locked securely (so I was locked in from the inside) as I was there by myself until 7.30am, when the next person started.

On the morning in question, I flicked the latch over on the security door but I didn't lock it with the key. I also locked the main door from the inside (again just flicking the latch across). After I had set up everything for the day inside, I went to unlock both doors, ready for any early kids that arrived. Then unlocked the main door and when I went to flick the latch on the security door, it wouldn't budge! I had to unlock it with my key, even though I never locked it with my key!
Another girl there told me one day she went to go to the toilet. The door was locked so she knocked on it and she heard someone yell out 'Hang on a minute' or something similar. So she waited in the staff room, which was next to the bathroom. She heard the toilet flush and waited for the person to come out. After about 5 minutes, nobody came out and the door was still closed. She thought it was a bit weird so she tried the door again and it opened! She looked in the bathroom and no-one was in there! She said she didn't see anyone come out of the bathroom! She said she would've seen the person come out of the bathroom, as she sat near the door of the staff room. Very strange.....

Another time, some girls were sitting in the staff room, facing the bookshelf. There were some old tea bags sitting on the top shelf, although not near the edge. Out of nowhere, they just 'leapt' off the shelf, onto the floor.
I remember having lunch in there one day and another girl was sitting opposite me at the table. There were several dirty mugs in the sink. The cups started clanging, as if someone was there washing them, but nobody was anywhere near the sink.