How to get values of custom Azure AD B2C user profiles properties – Facebook api

You can access custom claims by including them in the token sent to the app or by querying the Azure AD Graph API (not the Microsoft Graph yet).

1. Including custom claims in the token: In the Azure portal’s B2C blade, select the policy you are using, click on Edit, Application claims and select the custom attribute. Full documentation
2. Querying the Azure AD Graph API: Register an Azure AD application, query the Azure AD Graph API. Full documentation

Here’s some C# code for #2

// The client_id, client_secret, and tenant are pulled in from the App.config file
var clientId = "YOUR_CLIENT_ID";
var clientSecret = "YOUR_CLIENT_SECRET";
var tenant = "yourtenant.onmicrosoft.com";

var userObjectID = "OID_OF_THE_USER"
var query = "/users/" + userObjectId

this.authContext = new AuthenticationContext("https://login.microsoftonline.com/" + tenant);

// The ClientCredential is where you pass in your client_id and client_secret, which are 
// provided to Azure AD in order to receive an access_token using the app's identity.
this.credential = new ClientCredential(clientId, clientSecret);

// First, use ADAL to acquire a token using the app's identity (the credential)
// The first parameter is the resource we want an access_token for; in this case, the Graph API.
AuthenticationResult result = authContext.AcquireToken("https://graph.windows.net", credential);

// For B2C user managment, be sure to use the Azure AD Graph API for now.
HttpClient http = new HttpClient();
string url = "https://graph.windows.net/" + tenant + api + "?" + Globals.aadGraphVersion;
url += "&" + query;

// Append the access token for the Graph API to the Authorization header of the request, using the Bearer scheme.
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", result.AccessToken);
HttpResponseMessage response = await http.SendAsync(request);

if (!response.IsSuccessStatusCode)
{
    string error = await response.Content.ReadAsStringAsync();
    object formatted = JsonConvert.DeserializeObject(error);
    throw new WebException("Error Calling the Graph API: n" + JsonConvert.SerializeObject(formatted, Formatting.Indented));
}

return await response.Content.ReadAsStringAsync();