Mobile virtual reality (VR) head-mounted displays (HMDs) are steadily becoming part of people's everyday life. Most current interaction approaches rely either on additional hardware (e.g. Daydream Controller) or offer only a liMassachusetts Institute of Technologyed interaction concept (e.g. Google Cardboard). We explore a solution where a conventional smartwatch, a device users already carry around with them, is used to enable short interactions but also allows for longer complex interactions with mobile VR. To explore the possibilities of a smartwatch for interaction, we conducted a user study in which we compared two variables with regard to user performance: interaction method (touchscreen vs inertial sensors) and wearing method (hand-held vs wrist-worn). We found that selection time and error rate were lowest when holding the smartwatch in one hand using its inertial sensors for interaction (hand-held).