How do you know if your S9 has been tapped/being monitored?

[TechDeficit]

My calls echo at times, my battery seems to drain, and someone alluded to it.

 

[B. Diddy]

Welcome to Android Central! I'd say the vast majority of times, that kind of behavior isn't due to someone hacking your phone (unless you hold some position of considerable power or influence whose phone would be a prime target for organized hacker criminals). And remember, the average person shares so much personal information indiscriminately on social media that it can be relatively easy for someone to know a lot of details about their lives without having to dig too deep.

The call echoing issue is pretty common, and can be due to a number of issues. Sometimes, a case can cause this problem, if it's interfering with the phone's secondary noise-cancelling mic (typically at the top of the phone). Other times, it's a network issue.

Battery drain can be due to a multitude of reasons, very few of them having to do with malware or hackers. Two common reasons would be poor cell signal (which causes the phone to work harder to maintain the signal) or a poorly designed app that is using CPU when it shouldn't (a so-called "rogue app"). To get a better idea of what's using your battery, charge up to 100%, then let it drain to 20-30% with normal usage, without charging in between. Then show us:

1. The main Settings>Battery screen.
2. The fullscreen battery graph screen (which shows Awake time and Cell Signal Strength).
3. The Screen category (to see total Screen On time).
4. The Cell Standby category, if present (to see Time Without Signal).


http://forums.androidcentral.com/ge...ide-how-post-screenshots-android-central.html
You might have to install a 3rd party battery monitor, like GSam Battery Monitor, to get the Cell Signal Strength graph.