hello, is it possible to hear and watch someone’s phone without installing any malicious app? if possible how to protect from such activity? any advise would be helpful. thanks in advance!
short answer NO
Yes it is possible to do using many ways(more than 100) like browser exploit etc. For protection you should use latest antivirus, updated firmware, and everything should be kept updated.
If you can’t do this only step to protect yourself is THROW YOUR PHONE IN WATER then no one can then hack it.