When Delilah saw that he had told her all his heart, she sent and called for the lords of the Philistines, saying, Come up this once, for he has told me all his heart. Then the lords of the Philistines came up to her, and brought the money in their hand.
The fact that Samson told Delilah to do something to his hair (Judges 16:13) suggests that he was giving her a clue to his strength. She did not pick this up but kept hounding him for his secret. Finally he gave in (Judges 16:17; cf. Judges 14:17).