Program.cs

using Azure.Identity;
using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Graph;
using Microsoft.Extensions.Configuration;

namespace ConsoleGraphTest
{
    class Program
    {
        private static GraphServiceClient _graphServiceClient;

        static void Main(string[] args)
        {
            // Load appsettings.json
            var config = LoadAppSettings();
            if (null == config)
            {
                Console.WriteLine("Missing or invalid appsettings.json file. Please see README.md for configuration instructions.");
                return;
            }

            //Query using Graph SDK (preferred when possible)
            GraphServiceClient graphClient = GetAuthenticatedGraphClient(config);
            var requestOptions = new [] {new QueryOption("$top", "1")};

            var graphResult = graphClient.Users.Request(requestOptions).GetAsync().Result;
            Console.WriteLine("Graph SDK Result");
            Console.WriteLine(graphResult[0].DisplayName);
        }

        private static GraphServiceClient GetAuthenticatedGraphClient(IConfigurationRoot config)
        {
            var tenantId = config["tenantId"];
            var clientId = config["applicationId"];
            var clientSecret = config["applicationSecret"];

            //this specific scope means that application will default to what is defined in the application registration rather than using dynamic scopes
            var scopes = new [] {"https://graph.microsoft.com/.default"};

            var options = new TokenCredentialOptions
            {
                AuthorityHost = AzureAuthorityHosts.AzurePublicCloud
            };

            Func<DeviceCodeInfo, CancellationToken, Task> callback = (code, cancellation) =>
            {
                Console.WriteLine(code.Message);
                return Task.FromResult(0);
            };

            var deviceCodeCredential = new DeviceCodeCredential(callback, tenantId, clientId, options);

            _graphServiceClient = new GraphServiceClient(deviceCodeCredential, scopes);
            return _graphServiceClient;
        }

        private static IConfigurationRoot LoadAppSettings()
        {
            try
            {
                var config = new ConfigurationBuilder()
                .SetBasePath(System.IO.Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json", false, true)
                .Build();

                // Validate required settings
                if (string.IsNullOrEmpty(config["applicationId"]) ||
                    string.IsNullOrEmpty(config["redirectUri"]) ||
                    string.IsNullOrEmpty(config["tenantId"]))
                {
                    return null;
                }

                return config;
            }
            catch (System.IO.FileNotFoundException)
            {
                return null;
            }
        }
    }
}