Albert Barnes Commentary Judges 18:3

"When they were by the house of Micah, they knew the voice of the young man the Levite; and they turned aside thither, and said unto him, Who brought thee hither? and what doest thou in this place? and what hast thou here?" — Judges 18:3 (ASV)

It does not follow that they had known him before and recognized his voice, though it may be so. But the Hebrew text equally supports the meaning that they heard the voice of the Levite; and, attracted by it, went into the chapel (Judges 18:18) where Jonathan was. They were probably just starting on their journey but were still within the court or precincts of Micah’s house. Micah had evidently not told them of his house of God and his Levite. Their questions indicate surprise.