Use this phrase to talk about someone approaching you. Usually, the person who's approaching has some purpose. They may want to attack you, to look at you, to hug you, etc.
You can use the phrase "come in for ___":
Don't you hate it when someone you've just met comes in for a hug but you feel like, "Hold on, I barely even know you!"
Or you can say "come in to ___" followed by a verb:
I could see that she was coming in to grab me, so I backed up.