"Dear me" can express sympathy, I want to ask when a beggar want to get the sympathy, can he say "Dear me"?
As Barb says, "Dear me" is a slightly old-fashioned term that usually expresses surprise or concern:
"Dear me, look at the time. I must head home before it gets dark."
"Dear me, where on earth have I put my glasses?"
The phrase "poor dear" expresses sympathy.
"You poor dear, you mustn't let this accident upset you".
I can imagine a beggar, particularly in a literary context, saying "Pity me", "Take/Have pity on me".
not a teacher