Who overhears the To be or not to be speech in act 3 in Hamlet?

In Act 3, Scene 1 of Shakespeare's "Hamlet," the famous "To be or not to be" soliloquy is overheard by Polonius and Claudius. Polonius, along with Claudius, is hiding behind a tapestry to listen to Hamlet's thoughts on existence and suicide. Their eavesdropping sets the stage for further intrigue in the play, as they seek to understand Hamlet's state of mind.