WebApplookup is a browser hijacker app that some Mac users have suddenly found installed on their computer systems. Browser hijackers are seldomly installed willingly and instead spread themselves through deceptive distribution tactics. This manipulative behavior is what classifies adware and browser hijackers as PUPs (Potentially Unwanted Programs).
Although the exact moment WebApplookup installed itself onto the computer may have slipped past the user's attention, the same cannot be said about its activity. WebApplookup will immediately proceed to take over the web browser and modify its settings to promote a sponsored address, most likely a fake search engine. On Google Chrome, the app will exploit the 'Managed by your organization' feature to limit the user's access to certain options and features.
Having a PUP present on your system will not cause any direct damage but that doesn't mean that they do result in increased security risks. Browser hijackers are known for spying on the browsing habits of users. The information they go after includes the search history, browsing history, clicked URLs, engagement with ads, IP address, geolocation, etc. The most dangerous browser hijackers, however, will also attempt to access sensitive payment, banking, debit/credit card information that users might have saved to the affected browser.