A detection device may monitor emissions from a computing device, which may include radiation and/or radio waves from a computing device. The emissions may be electromagnetic (EM) radiation indicative of operation of components of the computing device. When the emissions reach or exceed an emissions threshold, the detection device may output an indicator. The indicator may indicate a violation of an operational policy that is associated with the emissions threshold. The indicator may additionally or alternatively indicate compliance with the operation policy. In some embodiments, the detection device may be implemented as an accessory such as a case, a cover, a light, or another type of accessory for the computing device.