用来
yònglái · HSK 5
in order to
用 (use) + 来 (come/to) = use [it] to → in order to
用 means 'use' and 来 here marks purpose, like English 'to' in 'a knife to cut bread'. So 用来 literally reads 'use-to', flagging the function or purpose of something.
用 — pictograph of a bucket or wooden pail
用 originally depicted a bucket or container, possibly a sacrificial vessel made of wood. Over time it was borrowed to mean 'to use' or 'employ,' losing its concrete object sense. The modern meaning 'use' has been standard since early classical Chinese.
来 — pictograph of a wheat plant with grain heads
来 originally depicted a stalk of wheat with drooping grain heads, and meant 'wheat' in oracle bone script. It was later borrowed phonetically to write the unrelated verb 'to come,' which became its dominant meaning. The original 'wheat' sense was taken over by 麥 (now 麦).