I think today we have all sorts of technological advancement for something that would be mark of the beast. But I don't think it is already here. It would not be something we would end up using without even realizing it. Everyone will have to make a choice. Whether to get the mark of the beast and worship the beast or be slain. It would be a decision everyone would make and not something happening without even realizing.
Revelation 13:15 And it was allowed to give breath to the image of the beast, so that the image of the beast might even speak and might cause those who would not worship the image of the beast to be slain. 16 Also it causes all, both small and great, both rich and poor, both free and slave, to be marked on the right hand or the forehead, 17 so that no one can buy or sell unless he has the mark, that is, the name of the beast or the number of its name.