In this paper, we propose a sensor-based interaction for ubiquitous virtual reality (U-VR) systems that users are able to interact implicitly or explicitly with through a sensor. Due to the advances in sensor technology, we can utilize sensory data as a means of user interactions. To show the feasibility of the proposed method, we use ComposAR as a test-bed that is a script-based interaction authoring tool for augmented reality (AR) systems. By adding sensor-based interaction features to ComposAR, a user can interact with virtual 3D contents through a sensor. We believe that the proposed method provides natural user interactions for UVR systems.