A method of an optical sensor apparatus which is to be used with a controlling device arranged for controlling an object having a long shape and flexible form of a material, includes: using a light emitting circuit to generate and output a light ray to a surface of a portion of the object; sensing the light ray reflected from the surface for multiple times to generate multiple images; detecting at least one motion image in the generated multiple images; and, determining a motion, an offset, or a rotation angle of the object, which is controlled by the thread controlling device, according to the detected at least one motion image.