The invention relates to an apparatus (2, 3), comprising a mating unit (20-1, 20-2) for releasably attaching the apparatus (2) to a medical device (1) or for releasably receiving at least a part of the medical device (1). The apparatus (2, 3) further comprises one or more optical sensors (25, 26) and/or one or more acoustical sensors (27) for determining information related to a condition and/or use of the medical device (1). The invention further relates to a system comprising such an apparatus (2, 3) and such a medical device (1), to a method (500, 600, 700) and a computer program (61) for determining information related to a condition and/or use of such a medical device (1), and to a computer-readable medium (60) storing such a computer program (61).