In order to link dynamically with the library you do:

gprbuild -v -aI/usr/include/simple-components\
         -aO/usr/lib[64]/simple-components\
          APPLICATION\
         -largs -lsimple-components\

To link statically:

gprbuild -v -aI/usr/include/simple-components\
         -aO/usr/lib[64]/simple-components\
          APPLICATION\
         -largs /usr/lib[64]/libsimple-components.a\

You  can  also  use the gpr file in your project files. The project file
uses the external variable Library_Type to control linkage. It can  take
values "relocatable" (default) or "static". For example:

   with components.gpr";
   project My_Project is
      for Main use ("My_Progran");
   end My_Project;

which can be built (dynamically linking to the library) as:

gprbuild -v -Pmy_project.gpr

or statically:

gprbuild -v -XLibrary_Type=static -Pmy_project.gpr

See also:
   /usr/lib/gnat - components.gpr
   /usr/include/simple-components - *.adb, *.ads
   /usr/lib[64] - libsimple-components.so.4.80-1
   /usr/lib[64]/simple-components - *.ali, libsimple-components.a
   /usr/share/simple-components - *.htm documentation, tests and examples

Release notes:

 o APQ persistence layer is not supported.
 o GNADE ODBC persistence layer is not supported.
