A cap assembly can include a cap holder device with a plug member and a cap holder. The cap holder device is positionable in an end of a conduit positioned along a roadway. The cap holder is carried by the plug member and includes a magnetic element and a connector. The connector is connectable to the magnetic element to the plug member such that the magnetic element is movable relative to the plug member so as to position the magnetic element for releasably holding a cap that covers the end of the conduit when the plug member is positioned in the conduit. The cap assembly can be a debris cap insertable in a conduit, an end of a pipe, or other opening.