I've had a few experiences that likely qualify.
First one:
I lived in an apartment that I shared with two other people. Over the time we lived there we each experienced unexplained phenomena. What I most often encountered was this, or a variation on it: I'd arrive home from work before my roomies got home. My bedroom was right off the kitchen so I'd walk into the kitchen, empty my pockets of keys, money, etc. on the kitchen table before going into my room to change my clothes. I'd go back into the kitchen and discover that something I'd just put on the table was missing. Usually my keys. It happened so often that I would just say out loud, "Okay, you've had your fun. I need my keys!" and go about my business around the apartment. Invariably within a short while, I'd open a cupboard or a drawer and there would be my keys, or wallet, or whatever had gone missing. With no one else in the apartment, I have no explanation for this. One of my roommates eventually freaked & moved out one night when she woke up to see pictures and other items she'd hung on her bedroom walls fall to the floor one at a time.
Second one:
One day, while living in a house shared with three other roommates, I was in my bedroom folding laundry when I peripherally saw someone walk past my bedroom door toward the bathroom. My room was at the top of a stairway, and the bathroom & other bedrooms were down the hall everyone had to walk past my door to get to them so I didn't think much about it at first. But this particular time only two of my roommates were home and had been watching television downstairs. Right after I noticed someone walk past my door, I heard my roomies burst out laughing downstairs at something on the tv. Puzzled, I went out in the hallway & checked the bathroom & other bedrooms. There was no one upstairs but me. Still have no explanation for the person I noticed walking past my room.
Third one:
Before we renovated our current house, my husband & I were used to the "ghost" upstairs. Frequently during the night, generally around 2am, we would hear the sound of someone upstairs getting out of bed & walking a few steps. Several overnight guests in our home whom we'd never told about this also mentioned or asked about hearing someone getting up & walking during the night. A few guests reported seeing a little girl, but I never saw that. Since we've remodeled the house we have never heard or seen anything odd again. (To add to the vibe, the original part of our house is over 160 years old and is built on land that was part of a Native American Pueblo prior to the arrival of the Spaniards. Our next door neighbor even discovered a skeleton a few years ago when doing some excavation in their yard for a building project. The University was called, an archaeology team came & removed what they identified as the remains of a Pueblo woman, dating back to before the Spanish Colonial period. We frequently find cool old pottery shards when digging in our yard.)
I don't know if believe in ghosts or not, but those experiences help me keep an open mind.