u/step-up-434

I suspect my husband has been having an affair for a few years and I suspect he has out hidden cameras in our home. I’ve searched but haven’t found any. But, when they are together early mornings, like 4:00am I can heard them talking. It’s a low whisper but I can hear their whole conversations. And on weekends I’ve caught my husband whispering and I can hear her. My question is what type of nanny cam, two way audio are they using? She is obviously in her home and my husband would have to be using WiFi. I’ve checked the remote, his watch and other suspicious items but can find nothing. How are they communicating and what devices are they using?