Creating a Cell label reference from a formula

Not sure is I can explain this correctly, but here goes.

E2 has been labled as _OC7001 and E3 as _OC7002

B1 has the entry _OC7001 but I am wanting to create this off the value in column A. I tried to achieve this in B2 by using =CONCAT("=_",A3) but that returns the text =_OC7002 and not the value of the cell reference by _OC7002.

How do I acheive this?