If you use your personal phone for work, can your employer see what's on it?

Question

Basically I have to use my personal phone for work oncall. Can your employer see what's on my personal phone? (Like photos and bank info and stuff)

Answer 1

No they cannot.   

Answer 2

Only if you show them voluntarily (regardless of what they say).

Answer 3

Only if you have given them that access.  

Answer 4

only if you let them