You can group installation targets into components, for example, “docs”, “libs”, “runtime”, etc.
add_library(libone libone.c)
add_executable(one main1.c)
install(TARGETS libone one DESTINATION /somedir COMPONENT comp_one)
add_library(libtwo libtwo.c)
add_executable(two main2.c)
install(TARGETS libtwo two DESTINATION /somedir COMPONENT comp_two)
This makes it possible to run cmake -DCOMPONENT=comp_one -P {your_build_dir}/cmake_install.cmake to install only the libone library and the one executable. When you issue make install all components are installed.