The Lookup control adds an item in the Zapp that enables the user to lookup possible values that can be entered in the text field. Select "Input" on the Simplify Toolbar, then click "Lookup" from the dropdown to start using the tool.
A magnifying class icon or a similar button next to a text field normally indicates that a lookup search field is present. Hover over the lookup, and the Designer will prompt you to click it to include it in your Zapp.
Note that you must click the field's button to capture it.
The lookup field will now appear in the mobile preview.
Once the lookup button is clicked, usually, a new page or dialog opens which displays search options or a list or table of possible results to select for the lookup text field. Add this page to the Zapp as you would any other page to allow the user to select a possible value and go back to the page where the lookup was added.
User input caching can also be enabled to autocomplete user queries, creating further efficiency within your Zapp. Please see the User Input Caching for more information.