I just created a widget inside my dialog in whose xtype=selection i.e checkbox. Is there any way through which i can get my custom value instead of true and false while select a
You can give this a try
{
  xtype: "selection",
  fieldLabel: "Yes/No",
  name: "./yesNo",
  hideLabel: false,
  type: "checkbox",
  allowBlank: true,
  jcr:primaryType: "cq:Widget",
  fieldDescription: "Check for Yes",
  options: {
      jcr:primaryType: "cq:WidgetCollection",
      option0: {
                value: "Yes",
                jcr:primaryType: "nt:unstructured",
                text: ""
               }
         }
}
And when reading it properties.get("yesNo","No")