Yes, it is possible to determine if there is spyware installed on your iPhone. The most effective way to check for spyware on your device is by using a reliable mobile security app. By running a full system scan with the app, you can detect any malicious software that may be present. Additionally, some signs that could indicate the presence of spyware include battery drain or unusually high data usage, sudden changes in performance such as decreased speed or crashing, and unfamiliar applications appearing on the device. If you notice any suspicious activity or behaviors from your phone, it's important to take action and remove any potential threats as soon as possible.