Is it possible to mining BTCitcoin without any capital/asset?
No... You need a computer, a mining software and electricity... those are all assets.
well not really, you can mine with a raspberry pi, instead of keep on your desktop, less electricity wasted with the first
and mining software is free btw
Even if you are using a Raspberry Pi 2, it will be a very small amount of coins made. I think gpu/cpu days are sadly over. Yes you could do it with a Raspberry Pi but it will not bring in a lot. And I would be surprised if you could pay for the Raspberry Pi from mining in a timely fashion.