Quote from Adoaver

Can someone explain the concept of spying to me? I'm trying to spy on someone and my research level is higher. But my spy probes keep getting shot down. Thanks!

thats normal and thats why they are so cheap.

In addition, I'll add a little further detail.

Generally, when you spy an empty planet (no fleet or defenses there) with one probe, you probably won't lose the probe, possibly even if your espionage level is lower than the opponent. But if you spy a planet with fleet or defenses on, there is a high likelihood that your probe will be destroyed, even if your espionage level is higher.

If you spy a planet with multiple probes, the possibility that you will lose those probes increases. This is even more likely if the planet has fleet or defenses, but is still possible if it is an empty planet (no fleet or defenses). The logic here just seems to be "stealth". One probe can escape "detection" better than a large group.

Then if your espionage level is too low to see the opponent planet details, you can add more probes to reveal more information, but this not only has the added risk of "large quantities=higher detection likelihood", but also that the target has higher espionage levels than you, so you are definitely going to lose your probes.

All this is just information about the game mechanics, and shouldn't stop you from using probes when you know they will be destroyed. As Xsuno says, they are cheap. Losing probes is not even a consideration in the game once you have grown your account beyond 1000 points...