@section Scripts {
	<script type='text/javascript'>
		function onSucces(content) {
			$("#result").text(content.Result);
		}
	</script>
}

@using (Ajax.BeginForm("Subscribe", "Home", new AjaxOptions() { OnSuccess = "onSucces", LoadingElementId = "loader" }))
{
	@Html.TextBoxFor(s => s.EmailAddress);
	<input type="submit" value="button" />
	<div id="loader" style="display:none">Even wachten!</div>
	<div id="result"></div>
}

How to submit a form asynchronously and get result in JSON

MVC Ajax Submit Form

form, ajax

C#