The Apple A7 is a 64-bit system on a chip (SoC) designed by Apple Inc. It first appeared in the iPhone 5S, which was introduced on September 10, 2013. Apple states that it is up to twice as fast and has up to twice the graphics power compared to its predecessor, the Apple A6. While not the first 64-bit ARM CPU, it is the first to ship in a consumer smartphone or tablet computer.
Apple Inc. i the only company to use a 64-bit system in a consumer smartphone or tablet computer. 
While it was the first company to put a 64-bit system in a smartphone or tablet, the context does not provide enough information to know if it is the only company to use them now. 