My keyboard is typing by itself, could there be a ghost in it?

If it is still in warranty, save yourself the hassle and just get it repaired or replaced.

If it is out of warranty, it could be one of a few things and there is no easy way to tell.

1. Malware (unlikely): Test via going to an Ubuntu or similar boot disk and open notepad/command line and see if the same thing happens
2. Loose Connection: Try taking the keyboard and reseating it. A bit of dust may have got on the connector, or it could just be loose. Putting a bit of pressure on the keyboard may be making a short circuit.
3. Bad Keyboard: It’s just faulty, need to replace it.
4. Bad Motherboard: Worst of the worst. A friend had an Acer laptop with a very similar diagnosis, it turned out that the same thing happened even with a new keyboard, but not USB keyboard. So the only thing I could say was the motherboard was faulty.
5. Debris: There might be some debris, like a paperclip or food, stuck under or between the keys. Try prising the keys off and shaking the keyboard upside-down to loosen it.
6. Ghost: Like your title says, there could actually be a ghost in there!

The "could there be a ghost in it" really got me laughing, What I can tell you is this, from my years of experience it's most likely a faulty keyboard which needs replacement.

But in order to be really sure, put your PC in airplane mode(disconnect from the internet), this is to be sure that a hacker/script isn't controlling your PC.

watch it for a couple of minutes and see if it continues to exhibit the same behavior if it doesn't, Kindly go to your nearest PC Engineer and get your keyboard fixed or replaced.

Good luck.