Here is an in-depth guide on how to get Umbreon in Pokemon Go.
1) Begin by catching an Eevee. Eevee can be found in the wild, or you can hatch one from an egg. Eevee can also be obtained through trades with other players or by purchasing one from the in-game shop using real money or Pokemon Go coins.

2) Once you have an Eevee, you need to collect 25 Eevee Candy to evolve it into Umbreon. You can get Eevee Candy by catching more Eevee, hatching Eevee from eggs, or transferring duplicate Eevee to Professor Willow. Each time you do one of these actions, you will receive one Eevee Candy.
3) Once you have enough Eevee Candy, tap on the Eevee you want to evolve and select the “Evolve” button. This will bring up a confirmation screen that shows you the evolution process and the resulting Pokemon.

4) To evolve Eevee into Umbreon, you will need to use one of the following names: Tamao, Sakura, or Chibi. These names correspond to the anime characters from the “Trouble’s Brewing” episode of the Pokemon anime, in which Eevee evolves into Umbreon after being exposed to a Moon Stone.
5) Once you have entered the correct name and tapped the “Evolve” button, your Eevee will evolve into Umbreon. The evolution process takes a few seconds to complete, and you will see the Eevee transform into Umbreon on the screen.

6) After evolving, Umbreon will be level 20 and will have the move “Last Resort.” Umbreon is a powerful dark-type Pokemon that is known for its high defense and special defense stats.
That’s all you need to do to get Umbreon in Pokemon Go! Remember that you can also evolve Eevee into other forms, such as Vaporeon, Flareon, and Jolteon, by using different names. These names are Rainer, Pyro, and Sparky, respectively.