Taming a monkey in Ark is not impossible, but it is very difficult. The most important part of taming a monkey is to find one that has enough affinity towards you.
Monkeys have to be comforted with a ~17000 point of Affinity taming process. This process will require you to use a ranged attack, such as a slingshot or bow, to inflict torpor. Then you will need to provide it with food, such as berries and vegetables, to build trust.
Once the monkey has been tamed, you will be able to give it commands to perform tasks such as gathering resources, crafting items, and defending against external threats. It is important to remember to keep it fed and happy to make sure that it behaves.