How can a keyholder detect if the cock is pulled out of the ball trap?

Hello everyone, I am usually quite creative, but here I want to hear your ideas on how a keyholder can tell if the chaste pulled his cock out of his chastity device? I own a CB6000, an eBay metal CD and currently wear the Holy Trainer. Of those three, HT is definitely more comfortable. I also use a DreamLover 2000 connected to it. Still, I can escape all of them with just my cock. My balls are firmly trapped and stay put until unlocked. I tried many things to physically stop the cock from being pulled out but they didn’t help much. Since I am lucky enough to have a girlfriend who is also my mistress and keyholder, is there a method for her to know when I’ve been naughty and played with myself without permission? The only idea I have is that she writes a letter or mark using waterproof lipstick at the base of the cock. If I try pulling the cock out, I’d grab it from the base so the lipstick would smear. And if she sees that, I get 200 cane strokes to make sure I never do that again. Any other suggestions?