SimpleInjector + ASP.NET Core

Program.cs

using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;

namespace WebApplication1
{
    public class Program
    {
        public static void Main(string[] args) =>
            CreateWebHostBuilder(args).Build().Run();

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>();
    }
}

Startup.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.DependencyInjection;
using SimpleInjector;
using WebApplication1.Services;

namespace WebApplication1
{
    public class Startup
    {
        private readonly Container _container = new Container();

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
            
            services.AddSimpleInjector(_container, options => 
                options
                    .AddAspNetCore()
                    .AddControllerActivation()
                    .AddViewComponentActivation()
                    .AddPageModelActivation()
                    .AddTagHelperActivation());

            services.AddScoped<IUserService, UserService>();
            services.AddScoped<ICompanyService, CompanyService>();
        }

        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            app.UseSimpleInjector(_container);

            if (env.IsDevelopment())
                app.UseDeveloperExceptionPage();
            else
                app.UseHsts();

            app.UseHttpsRedirection();
            app.UseMvc();
        }
    }
}

ValuesController.cs

using System.Collections.Generic;
using System.Linq;
using Microsoft.AspNetCore.Mvc;
using WebApplication1.Services;

namespace WebApplication1.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        private readonly ICompanyService _companyService;

        public ValuesController(ICompanyService companyService) =>
            _companyService = companyService;

        // GET api/values
        [HttpGet]
        public ActionResult<IEnumerable<string>> Get([FromServices] IUserService userService) =>
            _companyService.ListCompanies().Concat(userService.ListUsers()).ToList();
    }
}

WebApplication1.csproj

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.2</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore" Version="2.2.0" />
    <PackageReference Include="Microsoft.AspNetCore.HttpsPolicy" Version="2.2.0" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc" Version="2.2.0" />
    <PackageReference Include="SimpleInjector.Integration.AspNetCore.Mvc" Version="4.6.0" />
  </ItemGroup>

</Project>