In this After Effects tutorial, Dylan Wittmuss covers how to animate a map pin.
I'm just going to show how you can make an object look like it's falling in and poking or stabbing into something. In this case, I just have a pin dropping into the period of the letter here. It's really easy. You just have to of put a mask over it, but when I was first doing this, the mask just stayed in the same place the whole time, so that when the pin was dropping in, the mask was still covering up the bottom part of the pin here. To fix that, it's really easy. You just have to adjust the anchor points a little bit. I would put the key frames down of where you want your object to come in from, and then where you want it to land at. I have it landing right here.
Then once you have it positioned there, I would put in the mask, and so I have the mask inverted and it is just positioned at an angle over the bottom of the pin like this. Make sure you place a key frame over mask path here. Then I would scrub backwards to the start of when the object is falling, and you just want to adjust the anchor points of the mask so that it's really nothing here at the top. That way, when your object is moving in, there's nothing there. As long as you have a key frame placed here, the mask will start expanding as your object is moving. In my case, it doesn't expand over the pin until it's landed because it's such a short amount of time, but if you need to, I would place another key frame right before it lands so that way it only expands when you need it to.