The obvious connection is that Naso speaks of laws of a Nazir, and Shimshon is to be a nazir. But over Shabbos, I heard a beautiful alternative explanation. And of course, there could be multiple connections between the parsha and its haftarah. The suggestion is that the connection is rather to the laws of Sotah.
The story in the haftorah is basically one in which a woman has trouble conceiving with her husband (Shoftim 13:2), and suddenly a strange man appears to her whom neither she nor her husband knows (13:17), and now she will become pregnant. A jealous husband might react by being mekaneh his wife and suspecting her of cheating on him, and tell her not to see this man again. But Manoach prays to meet this man again (13:8), and speaks with him (13:11). And instead of being declared a mamzer, ch"v, Shimshon becomes a nazir and a shofet of Israel.