Form View:

<?xml version="1.0" encoding="utf-8"?>

<odoo>

       <data>

              <template id="assets_backend_accrediation" name="web_submit_ajax" inherit_id="web.assets_backend">

                     <xpath expr="." position="inside">

                           <script type="text/javascript" src="/your_module_name/static/src/js/your_js_file_name.js"/>

                     </xpath>

              </template>

              <record model="ir.ui.view" id="view_my_model_form">

                     <field name="name">my.model.name.form</field>

                     <field name="model"> my.model.name </field>

                     <field name="arch" type="xml">

                           <form string="Expense Type">

                                  <sheet>

                                         <group>

                                                <widget name="my_widget"/>

                                         </group>

                                  </sheet>

                           </form>

                     </field>

              </record>

       </data>

</odoo>

JavaScript

odoo.define('my_module.my_widget', function (require)

{

       var Widget= require('web.Widget');

       var widgetRegistry = require('web.widget_registry');

       var FieldManagerMixin = require('web.FieldManagerMixin');

       var MyWidget = Widget.extend(FieldManagerMixin, {

              init: function (parent, model, context)

              {

                     this._super(parent);

                     FieldManagerMixin.init.call(this);

                     this._super.apply(this, arguments);

              },

              start: function() {

                     var self = this;

                     this._super.apply(this, arguments);

                     var html ='<button id="btn_submit" class="btn btn-primary">Add Previous Compliance</button>';

                     this.$el.html(html);

                     this.$('#btn_submit').click(function(ev){

                           ev.preventDefault();

                           ev.stopPropagation();

                           alert("Submit button clicked");

                     });

              },

       });

       widgetRegistry.add( 'my_widget', MyWidget );

});