What you are associating with expensive mining hardware is probably ASIC mining. For some coins, like Bitcoin, such ASIC miners are mandatory but ETH, for example, is also mineable with GPU. Then there is the possibility to mine with your CPU. Here is Monero a good example. My guess is that with Neuroneum you are selling unused CPU power to mine?
Please I would like to know the difference between CPU and GPU. I Know CPU to be central processing unit which is available on household desktop and laptop, but the GPU seems strange to me. It will be great, if I can mine cryptocurrency with my laptop.