I personally haven't experienced anything I'd class as paranormal, but I do however believe there is more to this life than what we see. , meaning we as life have "tuned in " for want of another word to our perceived sense of reality.
I believe that from our own 3 dimensional world , other dimensions exist.
We'd have to be pretty ignorant to say that we understand everything about the universe, so this doesn't dismiss multidimensional extensions to our own, and maybe once in a while those dimensions interrelate with our own occasionally resulting in paranormal sightings.
I could be wrong, but that's what I believe.