Get Cookie value or Check if Cookie is exist?

Hi folks,
I am using Asp.net core

In login function Controller:

var claims = new List<Claim>
{
    new Claim(ClaimTypes.Name, model.Username)
};

var userIdentity = new ClaimsIdentity(claims,"login");

ClaimsPrincipal principal = new ClaimsPrincipal(userIdentity);

await HttpContext.Authentication.SignInAsync("CookieAuthentication", principal);

How to get cookie value or check if cookie is exist?

Waiting for your response. 

Thanks in Advance!