Sometimes you want to express a meaning in Chinese: verb + back and forth/to and fro/here and there/about, e.g. fly back and forth, move back and forth, walk here and there, etc. You can say literally 飞回来飞回去，移回来移回去，走到这里和那里, etc, but there is a formula of ~来~去 you can use to express the same meaning, making your sentence more idiomatic.
Formula of ~来~去
verb + 来 + the same verb +去 = verb back and forth/here and there/to and fro/about/around/up and down/hither and thither…
Examples:
We raced about the house to get our work done. 我们在屋里跑来跑去要把我们的工作搞完。
A brace of tame deer ran familiarly about the house. 一对驯鹿无拘无束地在室内跑来跑去。
The water was clear to the bottom. A school of tiny fish flicked hither and thither. 河水清澈见底，一群小鱼悠然地游来游去。
He jumps into the water and swims joyfully around.
他跳入水中，快乐地游来游去。
The big ugly one swam around with them.
这只又大又丑的小鸭跟着他们一起游来游去。
The planes are flying round and round.
飞机飞来飞去。
Bees are humming [buzzing] around from flower to flower.蜜蜂在花丛中嗡嗡地飞来飞去。
There are a lot of bats flitting about in the dusk.
黄昏时分有许多蝙蝠飞来飞去。
The children were jumping up and down, eg because they were very excited. 孩子们兴奋得跳来跳去.
Bacteria under the microscope, even those with no flagella, often bounce about in the water. 在显微镜下，细菌，甚至包括那些没有鞭毛的细菌，经常在水中跳来跳去。