The present invention is a device for determination of the presence of an installation space behind a ceiling covering for a retrofit recessed lighting fixture by way of a small probe hole. Specifically, the invention device comprises an longitudinal rotation handle with a top end and a bottom end defining a handle axis. Extending from the top end along the handle axis lies a first section of a narrow probe rod. The height of the first section exceeds the height of a retrofit recessed lighting fixture to be installed by at least the thickness of a ceiling covering through which it will be installed. At the end of the first section extends a second section perpendicular to the first section, where the second section comprises an insertion end which is pointed so that it can be pressed through the ceiling covering material to probe the space behind it.