SF_11.2, SF_12.0, SF_12.1, SF_12.2, SF_13.0, SF_13.1, SF_13.2, SF_13.3, SF_14.0, SF_14.1, SF_14.2, SF_14.3 - https://docs.sitefinity.com/for-developers-forms-events

IFormEntryUpdatedEvent_Bootstrapped_Global.asax.cs

using System;
using Telerik.Sitefinity.Abstractions;
using Telerik.Sitefinity.Modules.Forms.Events;
using Telerik.Sitefinity.Services;

namespace SitefinityWebApp
{
    public class Global : System.Web.HttpApplication
    {

        protected void Application_Start(object sender, EventArgs e)
        {
            Bootstrapper.Bootstrapped += Bootstrapper_Bootstrapped;
        }

        private void Bootstrapper_Bootstrapped(object sender, EventArgs e)
        {
            EventHub.Subscribe<IFormEntryUpdatedEvent>(evt => FormEntryUpdatedEventHandler(evt));
        }

        private void FormEntryUpdatedEventHandler(IFormEntryUpdatedEvent eventInfo)
        {
            var entryId = eventInfo.EntryId;
            var userId = eventInfo.UserId;
            var username = eventInfo.Username;
            var ipAddress = eventInfo.IpAddress;
            var submissionTime = eventInfo.SubmissionTime;
            var formId = eventInfo.FormId;
            var formName = eventInfo.FormName;
            var formTitle = eventInfo.FormTitle;
            var formSubscriptionListId = eventInfo.FormSubscriptionListId;
            var controls = eventInfo.Controls;
        }
    }
}