If you're concerned about this isn't the simple answer just to shut down at the end of the day?
While I'm sure there are exceptions, thinking about the IT departments I've worked with in the past and how cost-conscious they were, the last thing any of them would want to do is waste the time and money to record non-work related employee conversations at their home.
Well, what's to say that the PC is actually off? Many "enterprise" laptops nowadays can't have their battery pulled out easily.
My HP laptop needs to have the back panel removed. If I do that, it'll trip the intrusion sensor and wipe the TPM. IT can know about this and ask you why you're taking apart the laptop. If it's windows, and you don't have the BitLocker key, you won't even be able to turn it back on.
Then close it and wrap it in a couple layers of towels or something, stick it in your refrigerator under the leftover pizza, and/or block its access to wifi through your home router config. Physical controls trump whatever secret monitoring you fear it's doing.
While I'm sure there are exceptions, thinking about the IT departments I've worked with in the past and how cost-conscious they were, the last thing any of them would want to do is waste the time and money to record non-work related employee conversations at their home.