Examples are disclosed that relate to tracking a pose of a handheld object used with a head-mounted display device. In one example, a method comprises: receiving image data from an image sensing system; detecting a plurality of feature points of the handheld object in a frame of the image data; receiving inertial measurement unit (IMU) data from an IMU of the handheld object; based on detecting the plurality of feature points and receiving the IMU data, determining a first pose of the handheld object; determining that at least a portion of the plurality of feature points is not detected in another frame of the image data; using the IMU data, updating the first pose of the handheld object to a second pose; and body-locking the second pose of the handheld object to a body location on a user wearing the head-mounted display device.