Yes, although the risk of getting pregnant in this way is very low.
If you want to avoid getting pregnant, you should use contraception.
A man's semen (the liquid produced when he ejaculates or "comes") contains millions of sperm.
One ejaculation can contain more than 300 million sperm.
So, yeah, they're active enough to travel from on or around the vulva to inside the vagina if they're close enough to the vaginal opening.