What do you mean by "get an event from a dll"? Do you want the delegate signature? Do you want an object containing the event stub? Or is it a method handling an event?
I'll assume you aren't referencing this dll in your project, otherwise I doubt you'd be asking this (I would hope!).
You can programatically load an assembly like this:
dim assembly as Assembly = Assembly.LoadFrom(filePath)
From there, you can load all the types in the assembly into a list like this and process them:
dim types as Type() = assembly.GetExportedTypes()
for each t as Type in types
if t is delegate then
' do stuff
end if
if t.ImplementsInterface("IMyInterface") then
' do stuff
end if
next
The above assumes the dll was compiled in any managed language, it won't work on native dlls. If you are using a native dll, then you need to use the P/Invoke technique which I won't go into here.
If you email me more details, I might have an answer for you, but they are lacking here and I can't guess what you are looking for.