Retrieve the access rights of the specified security principal (team or user) to the specified record.
IOrganizationService _service; //Populate the CRM service
public void ReterivePrincipalAccess(Guid userId,EntityReference entityRef)
{
// Create the request object.
RetrievePrincipalAccessRequest access = new RetrievePrincipalAccessRequest();
// Set the properties of the request object.
access.Principal = new EntityReference("systemuser",userId); // GetUser id
access.Target = entityRef; //new EntityReference("account",new Guid("6db75ab3-5197-e911-80e7-c49ecd784764"));
// Execute the request.
RetrievePrincipalAccessResponse accessResponse = (RetrievePrincipalAccessResponse)_service.Execute(access);
accessResponse.Dump();
}