[HttpPost]
        public JsonResult FindPeople(String place)
        {
            return new JsonResult()
            {
                JsonRequestBehavior = JsonRequestBehavior.AllowGet,
                Data = new { result = "success" }
            };
        }

    <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/jquery.validate.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.js")" type="text/javascript"></script>

var getresult = function (data) {
        alert(data.result);
    };

 @using (Ajax.BeginForm("FindPeople", new { }, new AjaxOptions { OnSuccess = "getresult", HttpMethod = "post" }))
                        {
                            @Html.Hidden("place", Model.Warrant.workPlaceID) 
                            <button id="findBtn" type="submit">
                               <img src='@Url.Content("~/Content/images/save.png")' alt='' style="border:0;"/>@Html.Resource("Strings, Save")
                            </button>
                        }