No, for years keys and cars are programmed together so that they follow a similar algorithm which means the car is looking for a range of codes and the key emits a range of codes once a code is used the car will ignore it in any further instances and the key will roll on to it's next code based on the algorithm. So no you can't grab the code with some magical scanner because any signal you grab will from that point be ignored.
Let's be honest the remote only unlocks the car and unless it's a keyless entry/starting system it has nothing to do with the immobaliser, which is controlled by a seperate RFID chip. So why go to all the hassle of grabbing codes and fancy electronic devices which a good ol'e house brick will achieve the same result.