Albert Barnes Commentary 1 Samuel 13:6

"When the men of Israel saw that they were in a strait (for the people were distressed), then the people did hide themselves in caves, and in thickets, and in rocks, and in coverts, and in pits." — 1 Samuel 13:6 (ASV)

In thickets - This literally means “among thorns.”

High places - This does not refer to the high places for worship, but to holds or towers (Judges 9:46, 49). These were a particular kind of tower built by the old Canaanite inhabitants, which remained as ruins in the time of Saul.