I ground peppermints in my grinder (the same type as shown above) and it did well but left peppermint stuck to the bottom. It was difficult to get out with a damp cloth, so the only way was to either melt the peppermint out with hot water or chip it out with a knife and I did not want to scratch up the inside.
I was wondering if water was safe to put in the grinder, which is how I came across this. I wanted to pour hot water out of my electric kettle with a little dish soap and then turn it on to spin around inside until the peppermint was gone.
I poured the water and dish soap inside, and luckily all I had to do was swish it around a little a few times and the grinder was cleaned perfectly. I did not turn the grinder on at all, and it was unplugged the entire process.
The part I wanted to mention was that around the edge, I am seeing where water seeped inside a little. I have no clue if it got to the motor at all, but I am leaving the grinder upside down to dry out before I use it again in case. The edge around the silver pan that holds the blades is where the water seeped in. I also noticed that when I poured water in, some bubbles came up from around the blades which tells me water was able to get through around them as well.
While I cannot 100% say that I know how safe this is or what will happen (because I cannot see where exactly the water seeped into) I would not recommend putting liquid into one of these and starting it as it can easily seep through.
I realize the question at hand was about a few drops of water into dry substance which is a bit different, so I’m not sure how that would work. But I can say that water is able to get through into the casing of the grinder, so keep in mind when trying these things. As mentioned above, a blender is a better option if you have one.
If you are using more than a few drops that is already soaked into something else and likely won’t drip much, I’d highly advise against it (at least based on my experience).