VPN can help you hide your IP address from the unit conversion apps, but it may not be enough to prevent them from tracking you. Apps may also collect and share data using other methods, such as browser fingerprinting, tracking cookies, device identifiers, or permissions.  Even if you use a VPN, these methods can reveal information about your device, browser, location, preferences, and behavior. VPNs, then, are not foolproof solutions for online privacy, but rather useful tools that can enhance your security and anonymity.

Despite VPNs masking your IP address, apps can still collect and track the IP address of the VPN server you are connected to. Other identifying information may also be collected from your device or by other means.

The internet traffic you send and receive through a VPN is encrypted. The level of encryption can vary depending on the VPN protocol and settings. Although encrypted data is more difficult to interpret, it is not foolproof. It is possible for some apps to circumvent VPN encryption or collect data that is not encrypted.

VPNs can enhance your online privacy and security, but they cannot guarantee complete anonymity or prevent all forms of tracking by apps.

Additionally, you should check the privacy policies and settings of the apps you use and limit their access to your data.

In addition to using a secure browser that blocks third-party cookies and trackers, you should also regularly clear your browsing history and cache.

You may not be protected from all the threats to your privacy posed by these apps if you use a VPN.