In an ideal situation, you have no vulnerable IoT devices on your home / small office network, including televisions and security cameras, all your laptops have good anti virus software, and the operating systems are always uptodate, your wifi router is secure, or someone hasn’t hidden a WIFI Pineapple behind your sofa. So hopefully no bad guys are poking around your stuff.
There are 2 ways to know if you have a hacker infection on your network, firstly, analysing all the traffic in and out, some routers have such logging, features, but all but high specialist devices have the features to log bad behaviour and notify you (SIEMs). Secondly there are HoneyPots, they range in accessibility from $100 devices to tens of thousands.
There is little difference between their ability to warn you of a successful hacker, any HoneyPot will draw the attention of a hacker, and they won’t be able to resist scanning it for vulnerabilities. Where the difference comes between high end HoneyPots (and SIEMS) and the much cheaper HoneyPots, is the more expensive options will give you far more details on the intruder, but even the simplest HoneyPot will let you know your network was breached, it wont give you any indication of how bad, but of course any intrusion is pretty bad.
There is a great lack of awareness of the capabilities of HoneyPots, in the same user community who are rightly using antivirus solutions and even firewalls.
Think, leaving a pile of cash on your kitchen table, which no one can see from the outside, wired to a silent alarm, you would know very quickly if someone broke in through the backdoor.