There was a man of the hill-country of Ephraim, whose name was Micah.
This chapter  (Judges 17) is actually a preliminary introduction to  Judges 18, explaining the origin of that Danite shrine.  It tells of the founding of an illegal center of worship in the hill-country of Ephraim.  A part of God's Old Covenant with Israel was the restriction of the worship of God to the authorized tabernacle.  What Micah did in this chapter was a gross violation of God's commandments.