Like virtually every coin cell battery, the CR2032 is flat and round, much like that of a coin. These types of batteries fulfill a very important niche in the electronics industry. Often, a device will require a small amount of reserve electrical power to operate. However, squeezing in a cylindrical battery, such as a CR123A or AA batteries, would require the design as a whole to be adjusted. This would most likely make the electronic device clunkier and more unwieldily.
But with a CR2032 battery, fewer compromises need to be made. Their thin profile makes it very easy for manufacturers to find a convenient spot for the battery. As a result, they do not have to deviate as far from their original design and intention. With that in mind, CR2032 batteries have become extremely popular in the security industry, where it is often incredibly important to retain sensor designs that are small, discreet and compact. Users will typically encounter CR2032 batteries in smaller sensors and those with a thin profile. They are also often used in wireless key fobs.
It's easy to find examples of wireless alarm sensors that use CR2032 batteries. Honeywell in particular uses this type of coin battery in their equipment on a regular basis. In fact, Honeywell is such a big user of CR2032 batteries that they actually started producing their own Honeywell CR2032 3V Lithium Coin Batteries. Some examples of Honeywell Sensors that use CR2032 batteries include the Honeywell 5800MINI and the Honeywell 5834-4 Key Fob.