A very quick Google search found Haskelly [0] and Haskero [1] for VS Code, both of whose installation instructions say to install Intero [2] locally in your project directory with "stack build intero" if you don't want to use "stack install" to install Intero globally.

[0] https://marketplace.visualstudio.com/items?itemName=UCL.hask...

[1] https://marketplace.visualstudio.com/items?itemName=Vans.has...

[2] https://github.com/commercialhaskell/intero