A lie detector is read as fear of being found out, or a wish for honesty to be proven. Tradition links it to tension between what you feel and what you show.
Does the traditional reading fit your dream, or did it mean something else to you?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.