cache usually refers to a small amount of memory .
Your processor has
L1 data 64KB
L1 instruction 64KB
L2 cache general storage of data and instruction ranging from 128KB to 12MB
L3 cache general storage of data and instruction ranging from 0MB to 18 MB
Your hard drive also has 8MB to 64MB of cache memory.
Almost all motherboard devices ,Ethernet, sound card or chip, modem, bus timer,USB hubs,Video card etc all have small amounts of memory referred to as "CACHE".
There is nothing you can do for it . It is sealed in a package