// get photo
GraphServiceClient graphClient = GetAuthenticatedGraphClient(...);
var requestUserPhotoFile = graphClient.Me.Photo.Content.Request();
var resultUserPhotoFile = requestUserPhotoFile.GetAsync().Result;

// create the file
var profilePhotoPath = System.IO.Path.Combine(System.IO.Directory.GetCurrentDirectory(), "profilePhoto_" + resultsUserPhoto.Id + ".jpg");
var profilePhotoFile = System.IO.File.Create(profilePhotoPath);
resultUserPhotoFile.Seek(0, System.IO.SeekOrigin.Begin);
resultUserPhotoFile.CopyTo(profilePhotoFile);