Custom visual text input box

I want to add custom sub title for my visual. For that I want text box in property pane through which user can give input.

I have added following code inside "objects" key in capabilities.json, but it don't reflect in Format pane.

Your kind help will be appreciated.

"customTitle":{
      "displayName": "Custom Title",
      "displayNameKey": "Visual_CustomTitle",
      "properties": {
        "inputText": {
          "displayName": "Text To Show",
          "type": {
              "text": true
          }
        } 
      }
}