Get the value of custom attributes in .NET CORE 2.0 aspnet-identity

I'm using Identity with aspnet core 2.0 and I needed to add the nuCPF attribute in the ApplicationUser table. In the controller I am getting the user data as follows:

[Controller: ClientController )

public ClienteController(UserManager<ApplicationUser> userManager)
{
    _userManager = userManager;
}

[HttpGet]
public ActionResult Index(int paginaAtual = 1, string filtro = "")
{
    var NomeUsuarioLogado = User.Identity.Name;
    var idUsuarioLogado = _userManager.GetUserId(HttpContext.User);

    xxxxx.... etc
}

The ApplicationUser class looks like this:

public class ApplicationUser
{
    public int Id { get; set; }
    public string UserName { get; set; }
    public string NormalizedUserName { get; set; }
    public string Email { get; set; }
    public string NormalizedEmail { get; set; }
    public bool EmailConfirmed { get; set; }
    public string PasswordHash { get; set; }
    public string PhoneNumber { get; set; }
    public bool PhoneNumberConfirmed { get; set; }
    public bool TwoFactorEnabled { get; set; }
    public string nuCPF { get; set; }
}

Doubt 1:

How can I get the value of the nuCPF field?

Doubt 2: